Device with adjustable buoyancy with pressure compensation

ABSTRACT

The device for buoyancy is intended to be used by scuba divers. It allows the adjustment of its buoyancy and keeps this buoyancy constant even at changing water pressure. Its weight is low. The device works with a mechanism for pressure control. The controller keeps the pressure difference between the inside and the outside of the tank constant. The walls of the tank are expandable to allow the adjustment of the displaced volume.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to buoyancy compensators for scuba divers whichautomatically maintain a predetermined buoyancy.

2. Prior Art

The invention concerns a low-weight device for buoyancy which isintended to be used by divers. The force of buoyancy can be adjusted.Scuba divers usually need a device for buoyancy to compensate theirweight while diving to prevent them from sinking or floating to thesurface. The buoyancy must be adjustable because the diver's weightchanges while diving. Usually a kind of bag is used which is attached tothe body and which is filled with different quantities of air. Thebuoyancy of these diving devices depends on the air volume inside thebag. This volume is not constant, it depends on the water pressure. Asthe diver sinks the pressure rises with the depth, the volume decreases,the buoyancy decreases too and the diver sinks even faster. This isusually an undesired, sometimes a dangerous effect.

Several improvements have been made to provide a buoyancy compensatorwith constant, adjustable buoyancy:

East's U.S. Pat. No. 3,820,348 discloses an automatic buoyancy devicewith a flexible bladder between two rigid plates. The plates, togetherwith a cable mechanism, sense changes of the bladder volume andcompensate these changes by allowing the bladder to inflate or deflate.A disadvantage of this device is its rather complicated and bulkyconstruction.

Bohmrich's device (U.S. Pat. No. 4,114,389) consists of a rigid constantvolume chamber filled with air. By admitting water into the chamber thebuoyancy can be changed. Again this device is bulky and in additiondifficult to handle, as several valves must be activated to let thewater in or out.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an automatic buoyancycompensator maintaining a set buoyancy, which is simple to operate,lightweight, not bulky, comfortable to wear and cheap.

The device according to the invention is a device with an adjustablebuoyancy, which is almost independent of the water pressure. Inaddition, the weight of the device is low because the walls of thedevice are made of a light-weight material.

The buoyancy compensator consists of a container at which the displacedvolume depends on the pressure difference between inside and theambient. The pressure difference is measured, either mechanically orelectronically. The measured value is conveyed to a controller which inturn steers the valves through which air can be released or filled intothe tank. The air is received from the diver's compressed air tank. Thecontrolled pressure difference can be adjusted by the diver while divingand is kept constant at the selected value by the said pressurecontroller. Therefore the inner gas volume, and with it the buoyancy, iskept constant at the selected value too. The container is constructedwith expandable walls to allow the change of the volume in response tothe adjustments of the pressure difference. The adjustment of thepressure difference can be done by the diver at normal operation of thecompensator, i.e. without having to take it appart.

For a fuller understanding of the nature of the invention, referenceshould be made to the following detailed description of the preferredembodiments of the invention, considered together with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a first preferred embodiment of the invention.

FIG. 1B illustrates an alternate of the first embodiment.

FIG. 2A shows a second preferred embodiment.

FIG. 2B shows the buoyancy compensator in the shape of a diving vest.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a description of a first embodiment of the inventionand refers to FIGS. 1A and 1B.

The buoyancy compensator consists of an expandable and airtight bellows2 with a cover 1 and a bottom 3. The bottom is connected to the cover byan expandable rubber string or coil spring of metal 5. The bottom isequipped with two valves 7, 12. Through the valve 7 pressurised air fromthe diver's pressurised air tank can be fed into the container, throughthe valve 12 air can escape from the container. Pressure measuring means6 is provided to measure the pressure difference between inside, 4, andoutside. This means may be mechanical or electronic and is well known tothe skilled. The sensed pressure difference influences the controller10. This controller activates either the inlet valve 7 to increase thepressure inside the container, or the outlet valve 12 to decrease thepressure. The control mechanism is designed so that the pressuredifference is held constant to a adjustable value. This value may beadjusted by the diver while diving in order to change the buoyancy bythe knob 11.

Designs for adjustable pressure control mechanisms are well known to theskilled.

Depending on the selected value of pressure difference the rubber string5 will be more or less stretched. Therefore the inner air volume, andwith it the buoyancy, is kept constant at the selected value too.

FIG. 2a shows a container similar to that of FIG. 1A. The walls 18 aremade of an expandable, elastic material like rubber. Increasing pressuredifference will increase the length of the walls and therefore alsoincrease the displaced volume. The inner elastic string is omitted inthis construction. Via a flexible, but not expandable hose 17 a secondchamber 14 is connected to the first chamber 4. This chamber consistsagain of a bottom 16 and expandable walls 15.

This multi-chamber design allows the design of a diving vest (FIG. 2b)using this principle of buoyancy control. The vest is shaped as a jacketto be worn by the scuba diver. The jacket consists of many chambers 18which are connected to each other via hoses so that gas can pass fromone chamber to the next. The walls of the chambers consist of anexpandable, elastic material like rubber. The chambers can be inflatedor deflated according to the described mechanism. Rising pressuredifference between inside and outside will increase the volume ofdisplacement of the jacket.

While the present invention has been described in connection withparticular embodiments thereof, it will be understood by those skilledin the art that many changes and modifications may be made withoutdeparting from the true spirit and scope of the present invention.Therefore, it is intended by the appended claims to cover all suchchanges and modifications which come within the true spirit and scope ofthis invention.

What is claimed is:
 1. Adjustable buoyancy compensator for scuba divers,comprising:a hollow, airtight container, the volume of which depends onthe pressure difference between inside and outside of the container,valves through which air can be released from the inside to the outsideand can be fed into the container, means for measuring the air pressuredifference between inside and outside of the container, a pressurecontroller, which is stimulated by said means for measuring the pressuredifference, and which keeps the pressure difference constant by steeringthe input or output valves to release air from or to refill air into thecontainer, whereby the value of the pressure difference can be adjustedby the diver for adjustment of the buoyancy while diving and at normaloperation of the compensator.
 2. Compensator of claim 1,whereby thewalls of the container are shaped like the bellows of an accordion andare foldable and expandable, and whereby the top and the bottom of thecontainer are connected to each other by strings of elastic material orby metal springs.
 3. Compensator of claim 1,whereby the walls of thecontainer consist of an expandable, elastic material so that a change ofthe pressure difference between inside and outside of the containerchanges the length of these walls.
 4. Compensator of claim 3,whereby thecompensator consists of a multitude of chambers which are connected toeach other by flexible hoses, and whereby the compensator is shaped likea jacket.